Material handling device



M. SPINRAD ETAL MATERIAL HANDLING DEVICE Aug. 30, 1966 2 Sheets-Sheet 1 Filed May 28, 1964 R J N m0 R H N 09 M T T N W T E 4 A V NOW. L AE ML Y B FIG. 4

g- 1966 M. SPINRAD ETAL 3,269,563

MATERIAL HANDLING DEVICE Filed May 28, 1964 2 Sheets-Sheet z INVENTORS MALGOM SPINRAD AZLAQ ZLL ATTORNEY LESLIE w. GIBSON, JR.

United States Patent tion of Pennsylvania Filed May 28, 1964, Ser. No. 370,986 7 Claims. (Cl. 214-1) This invention relates to a material handling and transporting device and, more particularly, to apparatus adapted to engage a sheet in gripping relationship at a first station and to transport the sheet to, and deposit it at, a second station, either in a folded or unfolded condition.

The apparatus of this invention may advantageously be used in the garment industry, as it is especially adapted for removing sewn garments from sewing machine work tables and delivering and depositing these garments, either folded or unfolded, in stack relationship to each other at convenient holding or transfer stations.

While the apparatus of this invention is described herein with particular reference to the handling and transfer of sewn garments, it will be appreciated that the invention is not so limited, as it may be used in other endeavors where the transfer of sheets of material, both hard and soft, is desired. Representative of these may be mentioned, for example, printing, high speed duplicating, die cutting paper blanks for box making, and the like.

Thus, it is an object of this invention to provide mechanically simple, relatively inexpensive, reliable and efficient means for removing sheets of paper, cloth, and the like, from one location and depositing them at another location.

Another object of this invention is to provide apparatus for transferring a sheet from a first to a second station, which apparatus may be easily adjusted to permit variably selecting the locations where the sheet is engaged and deposited.

Yet another object of this invention is to provide a device that will fold a sheet as part of an operation of transferring the sheet from a first to a second station.

Still another object of this invention is to provide mechanical apparatus for removing sewn garments from sewing machine work tables and depositing the sewn garments in stacked relationship to each other at a preselected holding or transfer station.

And still another object of this invention is to provide convenient and elfective methods and means by which a sheet of material may be grasped by a mechanical transfer device.

These and other objects of this invention will become apparent from the following description of the drawings in which:

FIG. 1 is a perspective view of a preferred embodiment of the apparatus of this invention,

FIG. 2 is a somewhat schematic side elevation of apparatus constructed in accordance with this invention in a fully extended position.

FIG. 3 is a somewhat schematic side elevation of apparatus constructed in accordance with this invention in a partially extended position.

FIG. 4 is a diagrammatic view showing a suitable pneumatic system for operating and controlling the mechanisms shown in FIGS. 1 through 3.

FIG. 5 is a detail in side elevation of the upper portion of the apparatus shown in FIG. 1.

FIG. 6 is a perspective view of jaw element fitted with a guide stop.

In FIGS. 1, 2 and 3, a portion of a work table 1 is shown such as may be associated with a sewing machine to support garments being sewn. While not essential to this invention, it is convenient to utilize this work table 1 as a base upon which to mount the supporting yoke 2 of the apparatus of this invention. The yoke 2, in turn, supports an operating air motor 6 and a bell crank 16.

The operating air motor 6 carries a piston rod 8 that is supported for reciprocating rectilinear motion with respect to the axis of the air motor 6, as is conventional. The air motor 6, in turn, is pivotally supported in support yoke 2 by means of pin 7. By these means, air motor 6 and its piston rod 8 are free to rotate about the axis of pin 7.

Bell crank 16 is pivotally mounted in support yoke 2 by means of a pivot pin 17 that passes through the fulcrum of hell crank 16 to permit rotation of the bell crank 16 about the axis of the pivot pin 17. The end of the lower arm 18 of the bell crank 16 is pivotally engaged to the upper end of piston rod 8 by means of a clevis 9 and a clevis pin 11. The clevis 9 has an extension 12 (FIGS. 2 and 3) that supports a control screw 14 in a manner that permits axial adjustment of the control screw 14 with respect to the axis of air motor 6. By these means, the control screw 14 may be positioned to actuate the operating button 13a of air valve 13 when the piston rod 8 of air motor 6 is retracted to a preselected position.

An extension 24- is provided at the rear of support yoke 2. This extension 24 is attached to a ball and socket joint 25 that in turn is engaged with the lower end of radius rod 23 to permit this lower end of the radius rod 23 to turn freely with respect to support yoke 2.

A 'ball and socket joint 30 is attached to crank 29 and engages the upper end of radius rod 23 to permit this upper end of the radius rod 23 to turn freely with respect to crank 29. The radius rod 23, as so mounted, will maintain -a fixed distance between the points of attachment to extension 24 and the crank 29. In order that this distance may be varied for control purposes, the upper end of the radius rod 23 is slidably mounted in the ball and socket joint 30, and retained by a set screw (not shown). Alternatively, as shown in FIGS. 2 and 3, the effective length of the radius rod may be adjusted by means of a turnbuckle 28.

The crank 29 is secured to a head casting (sector) 35 by means of a nut and bolt at any selected drilled opening (35a) along the periphery of the head casting (sector) 35. Both the sector 35 and the crank 29 are pivoted for rotation about a pivot pin 22 which, in turn, is supported by the free end of the upper arm 21 of bell crank 16. A mounting bracket 33 forms a part of the head casting 35 and provides means for engaging and supporting operating arm 32. Note that mounting bracket 33 may be of the split sleeve type to enable axial adjustment of the operating arm 32. Screws 33a or similar means may be provided to secure operating arm 32 in a fixed position in bracket 33.

The operating arm 32 supports a spring-loaded air motor 34 that is pivotally attached to operating arm 32 by means of pivot pin 36. A piston rod 37 is carried by the air motor 34 and may be axially displaced in rectilinear reciprocating motion with respect to the air motor. The spring bias of the air motor 34 is such that it will tend to keep the piston rod 37 in its fully retracted position.

The free end of piston rod 37 carries a clevis 39 that in turn is pivotably engaged to one arm of an elbow lever 38. The other arm of elbow lever 38 is fixedly attached to movable jaw bar shaft 41.

Movable jaw bar shaft 41 and fixed jaw bar shaft 43 are mounted with their axes parallel to each other and normal to the plane in which the operating arm 32 moves. They are supported at one end in bearings 40 that form a part of operating arm 32 and at their other ends by end support bearing block 46.

Fixed jaw bar shaft 43 carries a plurality of rigidly attached fixed jaws 44 (only two are shown in FIG. 2) that are rigidly attached to the jaw bar shaft 43. The fixed jaw bar shaft 43 is secured at each of its ends in a manner that will prevent its rotation, and, accordingly, jaws 44 are secured in fixed spatial relationship to movable jaw bar shaft 41.

Movable jaw bar shaft 41 carries a plurality of mova'ble jaws 42 that are rigidly attached to the movable jaw bar shaft 41. Unlike the fixed jaw bar shaft 43, however, movable jaw bar shaft 41 is journaled for rotation at its ends, namely, at bearing 40 and at end support bearing block 46. Movable jaws 42, being fixedly attached to movable jaw bar shaft 41, will rotate with the shaft 41 when it is actuated as by elbow lever 38. These movable jaws 42 are so designed that they will mate in sheet-clasping engagement with fixed jaws 44 when piston rod 37 is in an extended position as shown in FIG. 3. If desired, gripping faces (not shown) may be provided on the mating surfaces of the jaws to aid in the frictional engagement of the elements with a sheet of material to be held therebetween. Such faces may be comprised of yieldable materials such as rubber or non-skid materials such as sand paper and combinations thereof. The length of the jaw bar shafts and the number of mating jaws they have attached may be varied, within limits, to meet operational conditions.

It is also a feature of this invention that the illustrated device may be assembled either for right or left hand operation. That is to say the mounting of the operating arm 32 and the jaw bar shafts 41 and 43 may be reversed from the position shown in FIG. 1 to enable grasping a sheet of material on the opposite side of the bell crank 16 and associated mounting. This not only adds flexibility to the device, but also enables mounting a right and left handed unit together for tandem operation if sheets of large width are being handled. Advantageously, to accomplish this, pivot pin 17 is replaced by an elongated drive shaft that is'fixedly attached to the fulcrums of both bell cranks 16, but it is pivotally mounted in bearings mounted on the two yokes 2. This links the motion of both bell cranks together and enables accurate coordination of the cooperative motion of the devices. Preferably, in an arrangement of this sort, only one operating motor 6 is used to drive both units by means of the connecting drive shaft although, with proper controls, the synchronous operation of two operating air motors could be coordinated.

As described above, provision is made for the rotation of the upper jaw bar shaft 41 and jaws 42 with respect to stationary jaw bar shaft 43 and jaws 44. If desired, this action may be reversed by attaching elbow lever 38 to jaw bar shaft 43, thus causing jaws 44 to rotate into contact with mating jaws 42 on the now stationary jaw bar shaft 41. This adjustable feature enables selecting the side of the sheet from which the sheet is engaged by the movable aws.

For purposes of simplicity and clarity, the required air lines, controls, and connections have been excluded from the drawings of FIGS. 1, 2 and 3. These necessary elements will now be described with particular respect to the diagram of FIG. 4, wherein a preferred pneumatic system for operating the device of this invention is schematically illustrated.

Primary control of the operation of the device of this invention is maintained by means of control valve 58. The housing of the control valve 58 is provided with an orifice for introducing air at elevated pressures (designated IN) and an orifice for exhausting air to the atmosphere (designated EXH). The valve body contained within the housing of control valve 58 is a simple sliding spool comprised of two pairs of air-directing conduits: one pair is contained within a first portion A, and the other pair is contained within a second portion B, of the spool. When the spool is in the upper position (as illustrated) portion A of the spool is so aligned with the orifices that high pressure air will be directed into conduit 61, and conduit 62 will exhaust to the atmosphere. (For convenience, this is called the A position hereafter.) When the spool is shifted so that portion B is aligned with the orifices of the control valve 58, high pressure air will be directed into conduit 62, and conduit 61 will exhaust to the atmosphere. (For convenience, this is called the B position hereafter.)

The positioning of the spool within valve 58 is controlled by two pilot valves (designated PLT) located at opposite ends of the spool. These pilot valves are subjected to equal air pressure in order that no unbalancing forces will exist at the ends of the spool. However, when air is relieved from one of these pilot valves as through operation of air valves 13 or 56, the air pressure within the other pilot valve will exert a force upon the spool tending to move it in the direction of the pilot valve from which pressure has been relieved. As schematically illustrated, valves 13 and 56 are spring biased to keep the valves normally in the shut position. When their control buttons, 13:: and 56a, are depressed, however, they will exhaust air from their respective pilot valves to the atmosphere.

Conduit 61 communicates via a combination ball check and reducing valve 59:: to the underside of piston 8a contained within air motor 6, and conduit 62 communicates via a combination ball check and reducing valve 59 to the upper side of piston 8a. Piston 8a carries a piston 'rod 8, and as described above, piston rod 8 has an extension 12 afiixed thereto which supports control screw 14.

Conduit 62 also communicates with the underside of piston 37a of spring loaded air motor 34. The spring 37b is biased to keep the piston rod 37 in its retracted position.

The reducing-check valves 59 and 59a in air lines 62 and 61 respectively are designed to permit the unimpeded fiow of high pressure air from control valve 58 to the upper and lower sides of piston 8a. This is true since the ball checks will be unseated by the incoming high pressure air. However, when air is being exhausted from either side of the piston 8a, the ball checks will seat and the exhaust air must pass through the reducing portion of the valves 59 and 590. By these means, control of the speed of piston 8a is obtained in both directions of travel, as the speed of the piston will be directly influenced by the restriction or setting of the reducing valve and, accordingly, by the rate at which the exhaust air is allowed to escape or discharge.

When the device is in its at rest position, that is at the end of a cycle of operation, the pilot valve 58 will be in the A position. It can be appreciated from FIG. 4 that when this condition exists, the piston rod 8 will be in its fully extended position due to the pressure of high pressure air on the lower side of piston 8a and atmospheric pressure (via conduit 62) on the upper side of piston 8a. Also, piston rod 37 will be retracted by the action of spring 37b and atmospheric pressure acting on piston 37a. This position of the device will remain unchanged until a cycle of operation is begun by depressing control button 56a.

When the control button 560 of air valve 56 is depressed, air is exhausted from the lower pilot valve, and the air pressure of the upper pilot valve causes the spool to shift into the B position. When this happens, high pressure air is introduced via conduit 62 to the upper side of piston 8a. Conduit 61 will now exhaust to the atmosphere, as controlled by reducing valve 59a, and the unbalanced pressures will cause piston 8a to move downward and retract piston rod 8.

Simultaneously, while the spool is in the B position, high pressure air will be introduced into air motor 34 to cause piston 37a to move piston rod 37 into its extended position. Conversely, when the spool is shifted into the A position, air is exhausted to the atmosphere from air motor 34 via conduit 62, and the spring bias provided by spring 3711 forces piston rod 37 into its retracted position.

The operation of this device can best be understood by reference to FIGS. 2, 3 and 4. In FIG. 2, the device is shown in its fully extended position just after the movable jaws 42 have opened to release a sheet of material. This result is obtained when piston rod 8 moves to the bottom of its stroke and control screw 14 depresses operating button 13a of air valve 13. Air is then exhausted from the pilot valve on one side of the spool of control valve 53 and the spool shifts to the A position. Air is now exhausted via conduit 62 from the underside of piston 37a and spring 37b forces piston rod 37 to retract, carrying with it clevis 39. As a result, elbow lever 38 rotates jaw bar shaft 41 and jaws 42 are moved away from jaws 44.

As conduit 62 is now open to the atmosphere, the air pressure on the upper side of piston 8a is exhausted to the atmosphere. Simultaneously therewith, air under pressure is introduced onto the lower side of piston 8a, thus driving piston rod 8 toward its extended position. This, in turn, acting through the previously described pivot points, causes bell crank 16 to rotate (counterclockwise as shown in the drawing) about its fulcrum 17. Due to the fixed distance between pivot pins 22 and 27 and the fixed radii described by the rotation of upper arm 21 and radius rod 23, crank 29 rotates clockwise about pivot pin 22. The summation of these movements, that is the rotation of the bell crank 16 carrying pivot pin 22 in a counterclockwise arc and the rotation of crank 29 about pivot pin 22 in a clockwise direction, results in moving operating arm 32 into a suitable position adjacent work table 1 to receive another sheet of material.

As can best be seen by reference to FIG. 1, a supporting plate 3 made of any formable material extends from the end of the work table 1 and is provided with certain cut out portions 4. When subject device is fully retracted, as described above, stationary jaws 44 are positioned directly over cut out portions 4 and movable jaws 42 are positioned so that when rotated, they will enter the cut out portions 4 from the underside of support plate 3 and move through the cut outs 4 and into gripping relationship with stationary jaws 44. It can be readily understood that the support plate 3 need not be mounted on the edge of a table, but can be positioned at a point over the table. In this instance, the plate 3 would be bent upwardly from the work table to elevate cut outs 4 in order that a clearance would be provided to enable the movable jaws 42 to rotate into sheet grasping relationship with stationary jaws 44. i p

The su porting plate 3 and its cut out portions 4 provide simple and effective means for grasping a sheet of material for removal from work table 1 with jaws 42 and 44. In addition, this simple device enables the sheet of material, if desired, to be folded along any line as it is picked up by the jaws. This is accomplished by advancing the material over the edge of support plate 3 and allowing it to hang downwardly therefrom. When the jaws are rotated into contact with each other and the material is withdrawn from the table, the material will be held folded by the jaws along the line defined by the material as it hung over the edge of support plate 3. By these means, if the sheet is grasped when it is flush with the edge of support plate 3, it will not be folded at all, and if a fold is desired, its location can be determined by the distance the sheet is allowed to travel beyond the edge of the support plate 3 before it is grasped.

Returning to the operation of the device, the operating arm will remain in a retracted position with the stationary jaws r44 superjacent the cut outs 4 of support plate 3 until air valve 56 is actuated to exhaust air from the lower side of pilot valve 5-8. In practice, air valve 56 may be manually operated when a sheet of material is properly positioned over support plate 3 or, if desired, may be actuated electrically as by a solenoid or mechanically as by any suitable linkage. The spool will then shift to the B position, causing high pressure air to enter conduit 62, and conduit 61 to open to the atmosphere. As a result, high pressure air will be led to the underside of piston 37a, piston rod 37 will extend against the bias of spring 37b to move elbow lever 38 which, in turn, will rotate jaw bar shaft 41 and cause jaws 42 to close in grasping relationship with jaws 44.

At the same time, the high pressure air in conduit 62 will be led to the upper side of piston 8m and cause piston rod 8 to retract. As can be appreciated from the above description, the retraction of the piston rod 8 will cause a clockwise rotation of bell crank 16 and a counterclockwise rotation of crank 29 that will result in operating arm 32 being carried to an extended position remote from the work table 1. FIG. 3 illustrates this device just after the jaws have closed, the piston rod 8 has begun to retract, and the operating arm has begun to move away from the table.

Piston rod 8 will continue to retract until the control screw 14 comes in contact with the operating button 13a of air valve 13 and air is exhausted therefrom. At this time the spool of control valve 58 will shift to the A position, the jaws will open, and the operating arm 32 will retract to the work table 1 and into position to receive the next sheet of material. As mentioned above, the speed of operation will be controlled by the setting of the reducers contained in valves 59 and 59a. While the reducingaball check valves 59 and 59a are herein described as being separate valves, they may be included in a single valve body or be integrally contained within control valve 58. A control valve incorporating these features may be obtained, for example, from Mead Fluid Dynamics Company as sold under the trade designation 401-U.

Various means are provided to adjust the movement of operating arm 32 and to select its terminal positions. These features can best be understood if the device is viewed essentially as a four-bar linkage comprised of a portion of yoke 2, radius rod 23, crank 29, and the upper arm 21 of hell crank 16. Of these, the upper arm 21 and yoke 2 are fixed in length. The length of the upper arm 21 is defined by pivot pins 17 and 22,and the effective length of yoke 2 is defined by pivot pin 17 and ball joint 25. With respect to the other two elements of this linkage, the length of radius rod 23 may be adjusted, as mentioned above, by moving ball joint 30 along the axis of the radius rod 23 (FIG. 1) or by adjusting turnbuckle 28 (FIGS. 2 and 3); and the length of crank 29 may be adjusted by mounting ball joint 30 in any of the drilled holes provided in crank 29. As best shown in FIG. 5, the fixed angular displacement between crank 29 and operating arm 32 may be varied by attaching the crank 29 in any desired hole 35a in the head casting 35.

Two further adjustments are possible. As operating arm 32 is slidably mounted in support bracket 33, it may be axially extended or retracted as desired. Lastly, the angular displacement of hell crank 16 during a given cycle of operation may be varied by altering the length of the stroke of the piston rod 8 of air motor 6. This is accomplished by screwing control screw 14 downward to decrease the are through which the bell crank 16 will move and screwing the control screw upward to increase this are.

Referring to FIG. 6, a useful accessory for use with this invention is shown. Here a guide clip 61 is shown attached to a stationary jaw 44. When the device of this invention is retracted to the work table to receive a sheet of material, the depending legs of guide clip 61 will engage the leading edge of a sheet as it advances over support plate 3. By these means, the leading edge of the sheet may be restrained from further advancement and squarely positioned at the edge of the support plate 3 for suitable engagement with the jaws when they are \7 7 actuated. Of course, if it is desired to fold the sheet by letting the sheet advance over the edge of support plate 3 before it is grasped, the guide clip 61 should not be used.

On occasions, it may be desirable to utilize the air that is exhausted from conduits 61 and 62 to help remove a sheet from the work table 1 and the support plate 3. For example, if the exhausts from these conduits are directed outwardly and/or upwardly from the edge of support plate 3, the resulting jets of air will act cooperatively with the device of this invention in freeing the sheets of material from the guide plate in order that it may more readily be removed from the work table and guide plate.

This invention has been described with particular reference to pneumatic operation and control due to the reliability and comparative inexpensiveness of such systems. It will be appreciated, however, that while a pneumatic system is preferred, the function of the device of this invention-is not so dependent. For example, a hydraulic system could readily be substituted for the air system shown. Also, with only slight modification, this mechanism could be electrically driven and controlled. This could be accomplished quite simply by replacing the air motors with solenoids and the air valves with switches. As it is well within the skill of the art to make such functional substitutions, further description of this invention is felt unnecessary, as the preferred embodiment thereof has been fully described above.

We Claim:

1. Apparatus for removing flexible sheets from a work table and depositing them at a holding station, comprising:

an operating arm pivoted adjacent its upper end for rotation within a substantially vertical plane;

a first and a second generally parallel and horizontally disposed jaw bar shafts mounted at one of their ends adjacent the lower end of said operating arm, said first jaw bar shaft being mounted for rotation in said operating arm and said second jaw bar shaft being fixedly positioned in said operating arm;

at least two pairs of jaw means mounted on said jaw bar shafts with one jaw of each pair mounted on said first jaw bar shaft and the other jaw of each pair cooperatively mounted on said second jaw bar shaft;

first motor means adapted to rotate said first jaw bar shaft;

means to rotate said operating arm within said plane and simultaneously cause the lower end of said operating arm to move in a predominantly horizontal plane;

said means to rotate and move said operating arm comprising a four bar linkage.

2. Apparatus according to claim 1 in which said four bar linkage is comprised of a stationary base element, a radius rod pivotally connected at one end to said base element and pivotally, connected at its other end to a first crank, said first crank being attached to the upper end of said operating arm and pivotally mounted at a point remote from said radius rod to one end of a second crank, and the other end of said second crank being pivotally mounted in said base member at a point remote from said radius rod connection.

3. Apparatus according to claim 2 in which an operating lever is attached to said second crank at a point adjacent the point where said second crank is pivotally mounted in said base member and in which second motor means are provided to move said operating lever.

4. Apparatus according to claim 3 in which said lever and second rank form a bell crank pivoted in said base member for rotation at its fulcrum.

5. Apparatus according to claim 1 including motor control means that cause said first motor means to rotate said first jaw bar shaft and open said jaws when said operating arm is adjacent said holding station.

6. Apparatus according to claim 3 in which said motor control means will cause said second motor means to effect the return of said operating arm to a point adjacent said work table substantially at the same time that said first motor means causes said jaws to open.

7. Apparatus according to claim 1 characterized in that a support plate for supporting said sheet of material is provided at said work table, which plate contains cut-out portions adapted for receiving said jaw means.

References Cited by the Examiner UNITED STATES PATENTS 687,281 11/ 1901 Spalckhaver. 2,179,446 11/ 1939 Dahlstrom 214147 2,580,472 1/1952 Smith 214-147 2,670,090 2/ 1954 Crawley 214-147 2,815,868 12/1957 Landman 214147 X 2,905,367 9/1959 Coutu 22337 3,075,634 1/1963 Schwacofer 214-1 X 3,080,983 3/1963 Blatt. 3,127,026 3/1964 Blatt. 3,131,837 5/1964 Heschl 22337 FOREIGN PATENTS 102,265 8/ 1962 Netherlands.

MARVIN A. CHAMPION, Primary Examiner.

JORDAN FRANKLIN, Examiner.

G. V. LARKIN, Assistant Examiner. 

1. APPARATUS FOR REMOVING FLEXIBLE SHEETS FROM A WORK TABLE AND DEPOSITIONING THEN AT A HOLDING STATION, COMPRISING: AN OPERATING ARM PIVOTED ADJACENT ITS UPPER END FOR ROTATION WITHIN A SUBSTANTIALLY VERTICAL PLANE; A FIRST AND A SECOND GENERALLY PARALLEL AND HORIZONTALLY DISPOSED JAW BAR SHAFTS MOUNTED AT ONE OF THEIR ENDS ADJACENT THE LOWER END OF SAID OPERATING ARM, SAID FIRST JAW BAR SHAFT BEING MOUNTED FOR ROTATION IN SAID OPERATING ARM AND SAID SECOND JAW BAR SHAFT BEING FIXEDLY POSITIONED IN SAID OPERATING ARM; AT LEAST TWO PAIRS OF JAW MEANS MOUNTED ON SAID JAW BAR SHAFTS WITH ONE JAW OF EACH PAIR MOUNTED ON SAID FIRST JAW BAR SHAFT AND THE OTHER JAW OF EACH PAIR COPERATIVELY MOUNTED ON SAID SECOND JAW BAR SHAFT; FIRST MOTOR MEANS ADAPTED TO ROTATE SAID FIRST JAW BAR SHAFT; MEANS TO ROTATE SAID OPERATING ARM WITHIN SAID PLANE AND SIMULATANEOUSLY CAUSE THE LOWER END OF SAID OPERATING ARM TO MOVE IN A PREDOMINANTLY HORIZONTAL PLANE; SAID MEANS TO ROTATE AND MOVE SAID OPERATING ARM COMPRISING A FOUR BAR LINKAGE. 